The state of California is concerned about a proposed EPA rule change that would lower federal standards for water quality. This rule would supersede California’s more stringent regulations and prevent the state from enforcing its higher water-quality standards.

California could challenge the EPA rule in federal court, arguing that the federal government exceeded its authority or unlawfully displaced the state’s powers. Courts can review whether a federal agency rule is lawful. California cannot simply nullify a valid federal rule; under the Supremacy Clause, valid federal law takes precedence over conflicting state law.

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